MILFORD, Ohio (AP) _ The chairman and chief executive officer of Structural Dynamics Research Corp. resigned Friday, becoming the fourth executive to leave over financial problems disclosed in September.

Ronald J. Friedsam will remain a director of the company, which provides computer software and engineering services for design, analysis, testing and manufacturing of mechanical products.

The board of directors elected Albert F. Peter, a founder of the company and board member, as acting chief executive officer. A search for Friedsam's replacement is under way.

The company said in September that it discovered operational problems that will cause a $30 million shortfall in pretax earnings. Shareholders since have filed a series of lawsuits demanding to be reimbursed for the losses.

The problems forced the suburban Cincinnati company to restate earnings for 1992, 1993 and the first half of this year.